Hi Colin,
The species in question may not be Typhlonectes as there are at least three other species coming into the country legally. These are Dermophis, Geotrypetes, and Icthyophis. All of these are terrestrial and will probably drown if set-up in the manner described in your link.
In the first link there is suspect information provided by the authors of the care sheet. For a couple of quick examples, the vesicles that form when the Typhlonectes is under osmotic stress are not "air filled" but are filled with fluid although they also occasionally develop when the skin is attacked by an unidentified nematode.
Colonies of Typhlonectes has been maintained in Europe as well in various institutions in the USA for multiple generations. Long term survivial and reproduction is linked to maintaining the animals in water that is acidic and is not more than moderately hard. Water that has a pH >7 and is too hard has been linked to increased mortality (particuarly in neonates) and appears to inhibit reproduction. (In collections, reproduction is both more consistant and results in larger litters when the water is soft and acidic).
Ed